Prospects for application of ultracold Sr$_2$ molecules in precision measurements

TL;DR

This paper theoretically analyzes the potential of ultracold Sr$_2$ molecules for high-precision measurements, focusing on frequency measurement factors relevant to testing fundamental constants.

Contribution

It provides a detailed theoretical analysis of factors affecting frequency measurements in Sr$_2$, including transition dipole moments, lifetimes, and Stark shifts, aiding future experimental efforts.

Findings

Identification of optimal vibrational levels for precision measurement

Calculation of two-photon transition dipole moments and lifetimes

Assessment of Stark shifts and Stark-cancellation trapping feasibility

Abstract

Precision measurements with ultracold molecules require development of robust and sensitive techniques to produce and interrogate the molecules. With this goal, we theoretically analyze factors that affect frequency measurements between rovibrational levels of the Sr$_2$ molecule in the electronic ground state. This measurement can be used to constrain the possible time variation of the proton-electron mass ratio. Sr$_2$ is expected to be a strong candidate for achieving high precision due to the spinless nature and ease of cooling and perturbation-free trapping of Sr \cite{Zelevinsky2008}. The analysis includes calculations of two-photon transition dipole moments between deeply and weakly bound vibrational levels, lifetimes of intermediate excited states, and Stark shifts of the vibrational levels by the optical lattice field, including possibilities of Stark-cancellation trapping.